/*
 * Copyright (C) Azureus Software, Inc, All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 * 
 */
package org.gudy.azureus2.core3.logging.impl;

import java.io.OutputStream;
import java.io.PrintStream;
import java.util.ArrayList;
import java.util.List;

import org.gudy.azureus2.core3.config.ParameterListener;
import org.gudy.azureus2.core3.config.impl.ConfigurationManager;
import org.gudy.azureus2.core3.internat.MessageText;
import org.gudy.azureus2.core3.logging.ILogAlertListener;
import org.gudy.azureus2.core3.logging.ILogEventListener;
import org.gudy.azureus2.core3.logging.LogAlert;
import org.gudy.azureus2.core3.logging.LogEvent;
import org.gudy.azureus2.core3.logging.LogIDs;
import org.gudy.azureus2.core3.logging.Logger;
import org.gudy.azureus2.core3.util.AEDiagnostics;
import org.gudy.azureus2.core3.util.AEDiagnosticsLogger;
import org.gudy.azureus2.core3.util.Debug;

/**
 * Logging tool
 * 
 * @author TuxPaper
 * @since 2.3.0.7
 */

public class LoggerImpl {
    private static final int MAXHISTORY = 256;

    private static final boolean bLogToStdOut = System.getProperty("azureus.log.stdout") != null;

    private boolean bEventLoggingEnabled = false;

    private PrintStream psOldOut = null;

    private PrintStream psOldErr = null;

    private PrintStream psOut;

    private PrintStream psErr;

    private List logListeners = new ArrayList();

    private AEDiagnosticsLogger alertLogger;

    private List alertListeners = new ArrayList();

    private List alertHistory = new ArrayList();

    private boolean logToStdErrAllowed = true;

    /**
     * Initializes the Logger and sets up a file logger.
     */
    public LoggerImpl() {
        doRedirects();
    }

    /**
     * Must be seperate from constructor, because the code may call a Logger.* method, which requires a loggerImpl to be not null.
     * 
     */
    public void init() {
        // temporarily set to true, to log any errors between now and setting
        // bEnabled properly.
        bEventLoggingEnabled = true;

        // Shorten from COConfigurationManager To make code more readable
        final ConfigurationManager config = ConfigurationManager.getInstance();

        boolean overrideLog = System.getProperty("azureus.overridelog") != null;
        if (overrideLog) {
            bEventLoggingEnabled = true;
        } else {
            bEventLoggingEnabled = config.getBooleanParameter("Logger.Enabled");

            config.addParameterListener("Logger.Enabled", new ParameterListener() {
                public void parameterChanged(String parameterName) {
                    bEventLoggingEnabled = config.getBooleanParameter("Logger.Enabled");
                }
            });
        }
    }

    /**
     * Set up stdout/stderr redirects
     */
    public void doRedirects() {
        try {
            if (System.out != psOut) {
                if (psOldOut == null)
                    psOldOut = System.out;

                psOut = new PrintStream(new RedirectorStream(psOldOut, LogIDs.STDOUT, LogEvent.LT_INFORMATION));

                System.setOut(psOut);
            }

            if (System.err != psErr) {
                if (psOldErr == null)
                    psOldErr = System.err;

                psErr = new PrintStream(new RedirectorStream(psOldErr, LogIDs.STDERR, LogEvent.LT_ERROR));

                System.setErr(psErr);
            }

        } catch (Throwable e) {
            Debug.printStackTrace(e);
        }
    }

    public boolean isEnabled() {
        return bEventLoggingEnabled;
    }

    /**
     * Redirects any incoming text to the logger
     */
    private class RedirectorStream extends OutputStream {
        protected PrintStream ps;

        protected StringBuffer buffer = new StringBuffer(1024);

        protected LogIDs logID;

        protected int logType;

        protected RedirectorStream(PrintStream _ps, LogIDs _logID, int _logType) {
            ps = _ps;
            logType = _logType;
            logID = _logID;
        }

        public void write(int data) {
            char c = (char) data;

            if (c == '\n') {
                if (!bLogToStdOut) {
                    ps.println(buffer);
                }
                log(new LogEvent(logID, logType, buffer.toString()));
                buffer.setLength(0);
            } else if (c != '\r') {
                buffer.append(c);
            }
        }

        public void write(byte b[], int off, int len) {
            for (int i = off; i < off + len; i++) {
                int d = b[i];
                if (d < 0)
                    d += 256;
                write(d);
            }
        }
    }

    // Log Event Functions
    // ===================

    /**
     * Log an event
     * 
     * @param event
     *            event to log
     */
    public void log(LogEvent event) {

        /**
         * This highlights bits of code which log, but don't bother to check whether logging is enabled or not.
         */
        // if (!bEventLoggingEnabled) {
        // new Exception("No logging check done!").printStackTrace(psOldErr);
        // }

        /*
         * ever wondered where a log is coming from? turn on log-to-file and breakpoint here if ( event.text.startsWith( "Added Listener")){ int n=0;
         * }
         */

        if (bLogToStdOut && psOldOut != null)
            psOldOut.println(event.text);

        if (event.entryType == LogEvent.LT_ERROR) {
            if (AEDiagnostics.isStartupComplete()) {
                // more recursive horrors here if we try and log too early
                try {
                    Debug.outDiagLoggerOnly("[" + event.logID + "] " + event.text);
                } catch (Throwable e) {
                }
            }
            if (logToStdErrAllowed && psOldErr != null && event.logID != LogIDs.STDERR) {
                psOldErr.println("[" + event.logID + "] " + event.text);
            }
        }
        if (bEventLoggingEnabled)
            for (int i = 0; i < logListeners.size(); i++) {
                try {
                    Object listener = logListeners.get(i);
                    if (listener instanceof ILogEventListener)
                        ((ILogEventListener) listener).log(event);
                } catch (Throwable e) {
                    if (logToStdErrAllowed && psOldErr != null) {
                        psOldErr.println("Error while logging: " + e.getMessage());
                        e.printStackTrace(psOldErr);
                    }
                }
            }

        // Write error to stderr, which will eventually get back here
        if (event.err != null && event.entryType == LogEvent.LT_ERROR) {
            Debug.printStackTrace(event.err);
        }
    }

    public void logTextResource(LogEvent event) {
        event.text = MessageText.getString(event.text);
        log(event);
    }

    public void logTextResource(LogEvent event, String params[]) {
        event.text = MessageText.getString(event.text, params);
        log(event);
    }

    public void addListener(ILogEventListener aListener) {
        logListeners.add(aListener);
    }

    public void removeListener(ILogEventListener aListener) {
        logListeners.remove(aListener);
    }

    // Log Alert Functions
    // ===================

    public void log(LogAlert alert) {
        String logText = "Alert:" + alert.entryType + ":" + alert.text;

        // Log all Alerts as Events
        LogEvent alertEvent = new LogEvent(LogIDs.ALERT, alert.entryType, logText);
        alertEvent.err = alert.err;
        Logger.log(alertEvent);

        synchronized (this) {
            if (alertLogger == null) {
                alertLogger = AEDiagnostics.getLogger("alerts");
            }
        }

        Throwable error = alert.getError();

        if (error != null) {

            logText += " (" + Debug.getNestedExceptionMessage(error) + ")";
        }

        alertLogger.log(logText);

        alertHistory.add(alert);

        if (alertHistory.size() > MAXHISTORY)
            alertHistory.remove(0);

        for (int i = 0; i < alertListeners.size(); i++) {
            try {
                Object listener = alertListeners.get(i);
                if (listener instanceof ILogAlertListener)
                    ((ILogAlertListener) listener).alertRaised(alert);
            } catch (Throwable f) {
                if (psOldErr != null) {
                    psOldErr.println("Error while alerting: " + f.getMessage());
                    f.printStackTrace(psOldErr);
                }
            }
        }
    }

    public void logTextResource(LogAlert alert) {
        alert.text = MessageText.getString(alert.text);
        log(alert);
    }

    public void logTextResource(LogAlert alert, String params[]) {
        alert.text = MessageText.getString(alert.text, params);
        log(alert);
    }

    public void addListener(ILogAlertListener l) {
        alertListeners.add(l);

        for (int i = 0; i < alertHistory.size(); i++) {
            LogAlert alert = (LogAlert) alertHistory.get(i);
            l.alertRaised(alert);
        }
    }

    public void removeListener(ILogAlertListener l) {
        alertListeners.remove(l);
    }

    public PrintStream getOldStdErr() {
        return psOldErr;
    }

    public void allowLoggingToStdErr(boolean allowed) {
        this.logToStdErrAllowed = allowed;
    }
}
